This study is directed at identifying and characterizing the physiological roles of gap junctions in the olfactory epithelium. New data have shown that olfactory receptor neurons are coupled to one another and possibly to non-neuronal cells in the olfactory epithelium of Necturus maculosus. Coupling was revealed by dye-transfer, by electrical measurements and by antibody labeling. Because gap junctions can be regulated by second messenger-dependent mechanisms, and because the same intracellular messengers that are elevated during odor transduction can activate these mechanisms, coupling of olfactory neurons to other cells in the olfactory epithelium is expected to be modulated during odor transduction. Changes in coupling could affect odor sensitivity. Studies are proposed (1) to examine the extent of intercellular coupling in the epithelium using dye-transfer with Neurobiotin(TM) and Lucifer yellow, (2) to identify the subtypes of gap junction proteins in the olfactory epithelium and their distributions by cloning and the use of molecular techniques, and (3) to evaluate the pathways that regulate olfactory gap junctions using dye-tracer and electrophysiological methods. Gap junctions are now known to be common throughout the nervous system and to have important functional consequences, but our understanding of their physiological roles is poor. These studies should provide greater knowledge of both the olfactory system and of gap junctions, a basic interneuronal feature that occurs throughout the central nervous system.